Screening machine and method



Mar. 6,1923.

" H. K. NAIARIAN.

SCREENING MACHINE AND METHOD.

4 SHEETSSHEET I.

FILED NOV. 22, I920.

INVENTOR Mar. 6, 1923. 1,447,355.

H. K NAJARIAN. SCREENING MACHINE AND METHOD.

FILED NOVIZZ, 1920. 4 SHEETS-SHEET 2.

INVENTOR Mai. 6,1923.

4 sukns-sum a.

H. K. NAJARIAN.

SCREENING MACHINE AND METHOD. r iuao NOV 22 1920 Mar. 6, 1923.

H. K. NAJARIAN SCREENING MACHINE AND METHOD.

4 SHEETS-SHEET 4.

FILED NOV.22, 1920.

Patented Mar. 6, 1923.

ldtmdi HERAND K. NAJARIAN, OF SALT LAKE CITY, UTAH.

SCREENING MACHINE AND METHOD.

App1ication filed November 22, 1920. Serial No. 425,591.

Toall whom it may concern:

Be it known that I, HERAND K. 'NAJAR- IAN, a citizen of the United States, residing at Salt Lake City, county of Salt Lake, 5 and State of Utah, have invented certa n new and useful Improvements in Screening Machines and Methods; and I do doclare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to the characters of reference marked thereon, which form a part of this specification.

The object of my invention is to produce a screening machine that will be low in first cost, will have large capacity, and will not have any vibrating or reciprocating or shaking screen cloth or frame liable to rapid wear and tear.

My invention, as hereinafter described,

relates to a screening machine in which the material to be screened is made to travel over an inclined screen-cloth mounted on a rigid framework, and in which, during the travel of the said material over the screencloth, a series of impulses are imparted in rapid succession to the said material through the screen-cloth and the supporting frame, said screen-cloth and the sup porting frame themselves remaining sub stantially stationary, but serving the purpose of a medium through which the impulse of a blow struck beneath the supporting frame by a hammer, is transmitted to the said material passing over the screencloth.

The impulse thus imparted to the maoff the surface of the screen-cloth, the traj ectory, or the path of itstravel, in the air, depending on the intensity of the impulse and the velocity of travel of the material over thescreen-cloth. As, of two particles of same specific gravity but of different size thrown into the air as above described, the larger particle will have the longer trajectory, when the two particles fall back to the surface-of the screen-cloth, the finer particles will fall back to a point closer to the point from which they were originally thrown off the surface of the screen-cloth. In thisuwa a'separation of thefine partiterial to be screened, lifts thesaid material.

.cles" from t e coarse particles is effected in.

the air, the fine particles falling on to'the apertures and drop into the undersize hop-' per; the coarser particles after receiving a series of similar impulses and traveling over the screen-cloth with a series of jumps, finally go over the end of the screen-cloth and fall into the oversize hopper.

The screening machines in common use at the present time that are used for fine screening, in order to obtain the necessary movement and the separation of the material over the screen, make use of various shaking or vibrating devices which vibrate or shake the screen or the frame in different ways, as for instance rotate the screen and the frame together in a circular path or vibrate it in its own plane or in a plane perpendicular to it. These rapid vibrations and movements on the screen-cloth and the frame on which the screen-cloth is mounted, cause rapid deterioration of the moving parts, due to wear or fatigue induced in the material of construction, thus necessitating frequent repairs and renewals.

In myv screening machine, a screen-cloth and the framework carrying same are substantially stationary during the operation of the machine. The only moving parts in the entire machine being confined to the hammer mechanism, as hereinafter described.

My screen is particularly adapted for screening and sizing of fine ores, salt, gravel, sand, fireclay, slack coal, powdered coal,- 'chemicals in various crystalline and powdered forms, and the like.

The principle of operation of my screen may be easily illustrated with a' number of billiard balls set in a row. WVhen a blow is struck upon the-ball at one end of the row, the impulse of the blow is transmitted through the intermediate balls to the last ball. inftheflrow, which last ball will be thrown forward with a velocity depending on the intensity of the blow. The intermediate balls remain perfectly stationary, serving only to transmit the impulse of the blow to the last ball. Thus, in my screen, a blow struck at the bottom of a transnutter frame is transmitted "throughthe body of the said frame and through the screen-cloth secured thereon, to the bed of material to be screened passing over the screen-cloth, lifting the said bed of material away from the surface of the screen-cloth. During this operation, the screen-cloth and the frame carrying same remain stationary, just as in the case of the intermediate billiard balls mentioned above as in illustration of the principle of my screening machine.

Referring to the accompanying drawings for a more complete explanation of my screening machine:

Fig. 1 is a vertical cross section of small type screening machine taken on line 11 of Fig. 3 in the direction of the arrows;

Fig. 2 is a cross section taken on line 2-2 of Fig. 1 showing end view of dust sealing device in the undersize hopper;

Fig. 3 is a front view of my screening machine viewed on line 33 of Fig. 1 in the direction of the arrows;

Fig. 4 is a cross section of part of screeir cloth and of the transmitter frame showing arched screen-cloth and step-like mounting of the screen'cloth on the transmitter frame;

Fig. 5 is a cross section of my large type machine taken on line 5-5 of Fig. 6 in the direction of the arrows;

Fig. 6 is a front elevation of same taken on line 66 of Fig. 5 in the direction of the arrows;

Fig. 7 is an end elevation of same taken on line 7-7 of Fig. 6 in the direction of the arrows; and

Fig. 8 is a section of my screening machine showing centrifugal hammer mechanism driven by a direct connected motor.

The screening machine is preferably made in two slightly different types, both of which however operate on the same principle. As above indicated, Figures 1, 2 and 3 show a small size of screen, while Figures 5, 6, and 7 cover a larger size having greater capacity.

In Figures 1, 2 and 3 the screen carrying mechanism comprises a transmitter frame which consists of a pair of spaced vertically disposed plates 1, the lower ends of which are mounted upon the free end of a springsteel plate 2, the outer end of said plate being mounted in a slot in a base casting 3. An anvil block 4 is mounted on the under side of the spring plate 2 and is secured to said plate 2 and said transmitter plates' l by means of rivets 5, the mounting of the opposite end of spring plate 2 being retained by means of rivets 6. The screencarrying edge of each plate 1 is stepped. as shown, and to the shorter sides of said steps'a plurality of intermediate bars 7 and side bars '8 extend transversely of said transmitter plates 1. The screencloth 10 is secured to the bars 7 and 8 by means of cross slats 11 clamped to the bars 7 and 8 by bolts 12. The undersize material which passes through the screen 10 falls upon boards 13, which constitute a hopper bottom and are arranged on both sides of the transmitter plates 1, as shown. For the purpose of sealing the joints between the plates 1 and the hopper bottoms 13, flanged members 14 are secured to the sides of the plates 1, as by rivets 15, and flanges 16 which aresecured to the under sides of the boards 13 extend upward between the edges thereof and the plates 1 into'the pockets provided between the members 14 and said plates 1. At each end of the hopper endboards 17 are secured to the hopper bottom 13 to retain the screened material in the hopper. The hopper bottom 13is supported upon standards18 and dividing walls are arranged forward of these supports to provide a chute 19 for receiving the undersize which passes through the screen and slides down from, the hopper bottom 13, and a chute 20 for receiving the oversize discharged from the screen 10. The base casting 3 is secured by means of embedded bolts 21 to a concrete base 22 which also carries said supports 18.

For the purpose of operating the transmission frame 1, means is provided to engage the anvil block 4', which may be a pneumatic, steam, or mechanical hammer, as indicated at 23. This hammer has the usual set 24 which directly engages the block 4, and steam or air or the like is carried to the hammer 23 by a conductor 25. The base of the hammer is provided with a plurality of jack screws 26 for the purpose of elevating the hammer to cause the set to engage the block 4 to support the weight of the frame 1 and screen 10 and take said weight from the spring plate 2. In this manner a blow transmitted by the piston (not shown) in the hammer to the set 24. is in turn transmitted to the frame, 21 and the screen 10 in the mannerabove specified without imparting bodily movement to said frame and screen. Thus, as the material is fed from the feeding chute 27 to the screen 10, the undersize is caused to pass through the screen and the oversize to be thrown forwardly therealong to-separate the two, as above described.

The screen 10 may be mounted in several different ways, as shown in the drawings. It may he stepped as by arranging it in several sections at different elevations, as

shown in Figures 1 and 4. It may he stepped and slightly arched, as shownin Figure 4, or it may be arched without step ping, as indicated in Figure 5.

In Figures 5, 6 and 7, the large size screen is shown. In this form, angle bars 28 are secured to the plates 1 for supporting 'the screen. A cross beam 29 has its upper end of the hammer,

rolled or enlarged, as indicated, and engages the plates 1 bypassing through slots therein, the edges of'which slotsare re-enforced by At each end of the beam 29 a guide holder 30 is secured to the under side'thereofand guide rods 31 are mounted therein andheld by set screws 39. Saidguide rods 31 extend downward into sockets in a base casting 32,

supported upon the ends of cross channelbeams 33. Springs 35 are mounted between the ends of the guide holder 30 and the ends of the base casting 32 at each end of the beam 29, the-guide rods 31 passingthrough said springs35. These springs are provided to receive the weight of the frame 1 and the screen 10 through themedium ofthe cross beam=29. At-the center' of thecross beam 29 the anvil block. 4 is secured to the under side thereof and is adapted to be engaged by the set 24 of the hammer23, "as in the other form: The'beam 29 and thehainmer' parts are enclosed by 111621115201 a dust shield 34, which is placed over'said beam andengages the same, and theshield 34 is retained by means of the bolts which 'connect the beam 29, the blocks 40 and the angleirons 41,

above described. For the purpose of taking the weight of the beam-29 and frame 1 off screw jacks 42 controlled by hand wheels are mounted in the castings 32 and have their upper ends in engagement with the guide holders 30. However, when desired to operate the machine, the screw jacks are withdrawn to allow the weight of the parts to rest upon the hammer set 24 and the springs 35. Bolts 43 are provided to secure the channel beams 33 to supporting members 122.

The screen 10 is carried upon a framework 36, which comprises a plurality of cross members secured to the angle irons 28 on the plates 1, the screen 10 being arched and fixed upon the upper ends of said cross members of the frame 36 by means of bolts 12. The under size, which passes through the screen, falls between the plates 1 into the hopper 119 directly below the screening mechanism. The over size is thrown off of the screen and falls into the chute 20.

Figure 8 shows the application of a centrifugal hammer. An unbalance pulley 47 is rigidly fastened to a shaft 48 mounted in a bearing 46, which is in turn attached to the under side at one 'end of the spring plate 45. To the upper side of the spring steel plate and directly above the point of attachment of the bearing casting a striking button 44 is attache The other end being spaced a'nd mainbv the impulse of a of the-spring. steel plate is setand fastened in a groove in abase casting 51, supported by external supports 122,: and fastened thereto by bolts'52. The shaft 48 is directly connected to the-shaft of an electric motor 50 by flexible coupling 49. The hammer mechanism is so locatedithat the'anvil block 4, under the transmitter frame 1 (Fig. 1) or the cross beam" (Fig, 5) comes within close proximity of the striking button 44. When the shaft 48'is rotated rapidly, the unbalanced pulley through centrifugal force created within the pulley causes the spring steel plate 45 to :reciprocate in a plane per-iv pendicular to the planevofthe spring steelplate, causing the button 44 to hammerthe anvil block 4 oncefor each revolution of the unbalanced pulley 47.

The operation described as follows In the small type of screen-shown in Figures 1, 2 and 3, the l1'ammer123is lifted up by screw jacks 26until theweight of ,the and the screen mounted on 1t, comes completely on :the set of the.

transmitter frame,

hammer. The'spring steel-"plate 2 serves only to hold thefra-me in place, in balance,

during the-operation of the'machine, and

to support the frame when the hammer is taken-awayfrom the IHEL'Cllll'lG." The piston in the hammer, strikes the" set of i the-hammer from below within the hammer, the impulse of the blow being transmitted to the transmitter frame and to the-screen, successively, and thence to the bed of material to be screened pass ing over the screen-cloth. The material to be screened is fed on to the screen from chute 27, the oversize going to the oversize hopper 20 and the undersize passing through the screen and dropping into the undersize hopper 19.

In the large type of screening machine, as shown in Figures 5, 6 and 7, when the machine is not operating, the frame 1 is lifted from the top of the hammer by screw jacks 42 controlled by hand wheels. When operating, the frame is lowered so that the weight of the frame and the screen comes on top of the set of the hammer. The operation of this type of machine is substantially the same as that of the small size of machine.

I claim:

1. A screening machine comprising a relatively stationary frame, a screen thereon, and a hammer having a set to receive the weight of the frame and screen, where blow of the hammer on the set will be transmitted through the set, frame and screen upward to material on the screen without movement of the frame and screen.

2. A screen machine comprising a pair of vertically disposed frame members, a screen of myscreen may be brieflynot' shown in the drawing,

particles tending carried by said members, a block on the members at their lower portions, and a hammer engaging the block and supporting the In a screening machine in which the naterial is passed over an inclined screen of upwardly curved arch formed profile which is unyielding and nndeflectable underthe weight of said material means-for applying force to said material from beneath through the said screen cloth periodically withoutv causing said screen to move or vibrate and with a uniform rate of concentration throughoutthe extent of said screen, said force lifting the bed of material away from the surface of the screen and by virtue of the difference in the trajectory of the different sized particles thus thrown in the air producing separation of the coarser particles from the finer particles, the coarser to segregate as a layer of uniform thickness farther away from the surface of the screen and the finer particles tending to segregate as a layer of uniform thickness nearer to the surface of the screen cloth, thus enhancing the passage of fine particles smaller than the opening in the screen through the openings without being obstructed by. to the surface of the screen.

4. A screening machine comprising a rigid of the hammer will have its block,

coarser particles falling back frame, a screenmounted on -the-frame in the form of arches andvso proportioned-as to be unyielding and nndeflectible under the weight of material to be screened passing over the screen, a plurality of vertically disposed members attached to said frame, a block on the members at their lower portions, a mechanical hammer having a set nor-. mally engaging said block and carrying the weight of said screen, frame, members and block, whereby the impulse of a blow of the said hammer on the set will be trans mitted through the, set, the members,the frame and the screen without movement thereof. i

5. A screening machine comprising a rigid frame, a screen mounted onthe frame, a plurality of vertically disposed members attached to said frame, a block on the mem bers at their lower portions, a mechanical hammer having a set normally. engaging said block and carrying the weight of said screen, frame, members and block, where y the impulse of a blow of the said hammer on the set will be transmitted through the set, the members, the frame and the screen without movement thereof, the set ofthe hammer normally engaging the block on the. members and adjustable means for disengaging said hammer from said block causing said block, members, frame. and screen to be supported by external means.

In testimonywhereof I affix my signature.

HERAND K. NAJARIAN. 

